As a related art, International Patent Publication No. WO2004/098960A1 discloses an electric steering lock device. As shown in FIGS. 1 and 2, an electric steering lock device 100 includes: a worm gear 102 fixed to the rotational shaft of a motor 101; a worm wheel 103 engaged with the worm gear 102 and rotatably supported; a first cam member 104 integrally disposed on one side of the worm wheel 103; a second cam member 105 integrally disposed on the other side of the worm wheel 103; a lock member 106 following the first cam member 104 to move up and down; and a holding lever 107 following the second cam member 105 to oscillate.
The lock member 106 is shifted between a lock position (position of FIG. 1) preventing the rotation of a steering shaft 108 and an unlock position (position of FIG. 2) allowing the steering shaft 108 to rotate. A detection pin 106a protrudes from the lock member 106. A first position sensor S1 is placed on the movement orbit of the detection pin 106a. The first position sensor S1 outputs an ON signal when the lock member 106 is positioned at the lock position.
The holding lever 107 oscillates about a rotation pivot 109 between a standby position (position of FIG. 1) allowing the lock member 106 to move and a holding position (position of FIG. 2) preventing the movement of the lock member 106 to the lock position side. On the rotation pivot 109, a spring 110 is held that urges the holding lever 107 to the holding position side. In the lower end of the holding lever 107 is formed a “V” shaped hole 107a and in the hole 107a is inserted a pin 111a of a detection block 111. The detection block 111 is disposed to be movable in the up and down directions, and is moved upward and downward by the oscillation of the holding lever 107. A detection pin 111b protrudes from the lower end of the detection block 111, and a second position sensor S2 is placed on the upward and downward movement orbit of the detection pin 111b. The second position sensor S2 outputs an ON signal when the lock member 106 positions at the lock position and at the unlock position, and outputs an OFF signals when the lock member 106 positions at other positions.
In the above configuration, as illustrated in FIG. 1, the lock member 106 is supposed to be positioned at the lock position. In this state, the driver or the like presses a steering lock-unlock button (not shown) in order to drive a vehicle. Then the worm wheel 103 is rotated in an unlock direction C by driving the motor 101 and the lock member 106 follows the first cam member 104 to move in an unlock position direction D. Thereafter, as shown in FIG. 2, the lock member 106 moves to the unlock position, the holding lever 107 also follows the second cam member 105 to move in a holding position direction E, and then a latch fragment 107b of the holding lever 107 is inserted in a latch concave part 106b of the lock member 106. Then, although the output of the first position sensor S1 maintains an OFF signal state, the output of the second position sensor S2 changes from an OFF signal to an ON signal. This signal change stops the driving of the motor 101 and then the lock member 106 stops at the unlock position of FIG. 2. When the lock member 106 positions at the unlock position, the steering shaft 108 freely rotates. Since the position of the lock member 106 is held by the holding lever 107, the lock member 106 does not move to the lock position side even when a strong impact force is applied to the lock member 106. This securely prevents a situation in which the steering shaft 108 is locked during the traveling of the vehicle, or the like.
On the other hand, in the above configuration, as illustrated in FIG. 2, the lock member 106 is supposed to be positioned at the unlock position. In this state, the driver or the like presses the steering lock-unlock button (not shown) for the parking of the vehicle, or the like. Then, the worm wheel 103 is rotated in an lock direction F by driving the motor 101 and the holding lever 107 follows the second cam member 105 to move in a standby position direction G and also the lock member 106 follows the first cam member 104 to move in a lock position direction H. Thereafter, as shown in, FIG. 1, when the lock member 106 moves to the lock position, the output of the first position sensor S1 changes from an OFF signal to an ON signal, and the output of the second position sensor S2 also changes from an OFF signal to an ON signal. This signal change stops the driving of the motor 101 and then the lock member 106 stops at the lock position. When the lock member 106 positions at the lock position, the rotation of the steering shaft 108 is locked. This can prevent vehicle robbery while the vehicle is parked.